This invention relates to a control device for a camera shutter. The usual technique of releasing consecutively the opening and closing members for effecting the exposure operation of a shutter involves, in general, a control using a conventional mechanical delay mechanism as well as a control using an electromagnet connected with an electronic delay circuit.
Although the latter system can be simplified from the standpoint of the mechanism, its structure is rather complicated because there are several problems to be solved with regard to electrical insulation, connection of the electromagnet, etc. in obtaining the necessary coaction between electrical or mechanical signals.
One object of this invention is to improve the latter system, which is superior in exposure time precision and also has a higher performance reliability in the case of repeating operations, by its further simplification so as to make it inexpensive to manufacture as well as suitable for use in any small-size camera.
There are two types, in general, of focal-plane shutter for camera, which carry out exposure control through consecutive releases of said opening and closing members:
The first type in which the first and second blinds made of a cloth travel in the horizontal direction of the camera and the second type in which the blinds made of a cloth or metallic sheet travel in the vertical direction of the camera.
In the second type of shutter, a control mechanism for controlling the first and second blinds is arranged on one side in the horizontal direction of the camera and therefore some horizontal deviation in lens arrangement is inevitable for composing the shutter into a camera to form an obstacle from the stand-point of convenient operation if a small-size camera is to be designed, so that it is desired to reduce the space where said control mechanism is arranged.
On the other hand, said first type of shutter makes it possible to arrange a control mechanism in the vertical direction of the camera, resulting in few obstacles as mentioned above but it is disadvantageous, in comparison with said second type, from the standpoint of productivity, performance, etc.
Another object of this invention is to reduce the size of said control mechanism so that the shutter can be adapted to a small-size camera.
Said first object can be attained if, in connection with the shutter release, a contact for initiating operation of an electronic circuit for exposure control and the winding of an electromagnet for exposure control are insulated from the body of the camera and at the same time, for improving the performance of said electromagnet and simplification of connecting means, a fitting base plate for arranging the control mechanism is provided with a contact support, a winding frame of said electromagnet and a supporting shaft for each operating member are formed in one body from synthetic resin.
Such a base plate like this makes it possible to reduce the size of a simplified and less expensive shutter.
Said second object can be attained if as a member having multiple functions, a base plate arranged and supporting the control mechanism is formed in one body out of synthetic resin and as a result, it becomes possible to realize such a function and reduction in size which have not heretofore been possible with any conventional metallic plate.
Referring now to the drawings, one embodiment of the present invention is described in detail in the following.